Safety device for closure members



Dec. 30, 1958 i H. w. HEINRICHS SAFETY DEVICE FOR CLOSURE MEMBERS Filed May 14, 1957 2 Sheets-Sheet 1 Harry W. He/b/v'cbs INVENTOR.

Dec. 30, 1958 H. w. HEINRICHSI ,5

SAFETY DEVICE FOR CLOSURE MEMBERS Filed May 14, 1957 2 Sheets-Sheet 2 INVENTOR.

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2,866,659 SAFETY DEVICE FOR CLOSURE MEMBERS 9 Harry W. Heinrichs, Tulsa, Okla. Application May 14, 1957, Serial No. 659,061

3 Claims. (Cl. 292267) The present invention relates to safety devices for closure members, and more particularly to apparatus for releasably retaining vertically movable closure members in upper positions.

' The invention has utility in a number of arts in which the accidental falling of a relatively heavy closure member' constitutes a safety hazard; and it will be illustrated by way of example in connection with vertically reciprocable furnace doors.

In the case of such heavy closure members, it is common practice to provide some means such as a catch or a counter balance, for maintaining the closure member or door in an upper position so as to leave the hands free forperforming work in the space closed by the closure member. It occasionally happens that the means for maintaining a door or other closure member open willfail, and that the closure member will fall on the hand of the operator. For example, the cable of a counter weight may break, or the spring of a spring catch may weaken and fail; but whatever the source of failure, a rather serious accident can result from the resulting fall of the closure member.

Although many attempts have been made to overcome thev foregoing and other difficulties and disadvantages associated with this problem, none, so far as is known, has been entirely successful when practiced commercially on an industrial scale.

Accordingly, it is an object of the present invention to provide a safety device for closure members which will prevent inadvertent falling of the closure member upon failure of the closure operator.

Another object of the present invention is the provision ofapparatus for releasably retaining a Vertically movable closure member in an upper position, which will be automatically rendered operative by movement of the closure member into an upper position, and which will be rendered inoperative by a. single movement of the parts thereof.

' Still another object of the present invention is the provision of apparatus for releasably retaining a vertically movable closure member in an upper position, in which the operator must remove his hand from below the closure member in order to actuate the releasing mechanism.

A still further object of the present invention is the provision of apparatus for releasably retaining a vertically movable closure member in an upper position, which may be installed on existing closure structures withonly slight modifications thereof.

Finally, it is an object of the present invention to provide apparatus for releasably retaining vertically movable closure members, which will be simple and inexpensive to construct, easy to install and operate, and safe, dependable, rugged and durable in use.

Other objects and advantages of the present invention will become apparent from a consideration of the following description, taken in conjunction with the accompanying drawings, in which:

apparatus according to the present invention, shown in' its operative position in use in connection member or door of a furnace;

Figure 2 is the upper portion of Figure 1, but showing the safety device in its disengaged position prior to lowering of the closure member;

Figure 3 is an enlarged isometric view of the cam and hand lever assembly of the safety device of the present invention; and I Figure 4 is an isometric view of thesafety device according to the present invention, with parts broken away for clarity.

Referring now to the drawings in greater detail, there is shown a furnace indicated generally at land comwith the closure prising a fire box 3 of which the walls are largely made up of a ceramic material such as fire'clay or fire brick. Extending upwardly from the fire box is a plurality of upright standards 5 bearing crosswise at their upper ends a horizontal channel member 7 having a vertical web and a pair of inwardly extending horizontal flanges. A sheave 9 is mounted on channel member 7 for rotation about a horizontal axis. Trained over sheave 9 is a cable which at one end supports a closure member for fire box 3 comprising a door 13. At its other end, cable 11 supports a counterweight (not shown) for balancing the weight of door 13 and for enabling easy opening and closing of door 13. Thus far, the structure described is conventional.

The safety device of the the following structure:

Mounted within the channel of channel member 7 as by welding or the like is a pair of spaced brackets 15, between and through the upper portions of which is mounted a fulcrum 17 having an enlarged central portion 19 spaced from both brackets 15. A pair of frame members comprising swing bars 21 is mounted for rotation on fulcrum 17 between the shoulders formed by the outer ends of central portion 19 and the inner side faces of brackets 15. Swing bars 21 depend generally downwardly from fulcrum 17. Farther down along swing bars 21 and extending between and through bars present invention comprises 21 is a pin 23 on which is rotatably mounted a roller 25 disposed between bars 21. Roller 25 comprises a detent. Mounted on the upper side of door 13 is an upwardly extending clevis 27 within the yoke of which is pivotally secured the lower end of an elongated lock bar 29 which in turn extends generally upwardly from door 13. Lock bar 29 has at least one notch 31 on the inner side thereof; and in the embodiment shown, two notches 31 are provided, having identical configurations and spaced along the inner side of bar 29. Each notch 31 has an arcuate upper portion 33 complementary to the cylindrical periphery of roller 25 and adapted to engage over roller 25 so that lock bar 29 and door 13 may hang from roller 25 when a portion 33 is engaged over roller 25. Each notch 31 also has a lower portion 35 which may be straight or of substantially greater radius of curvature than portion 33 and which extends upwardly and inwardly from the inner side of lock bar 29.

A cam 37 is rotatably mounted on a pin 39 extending through and between swing bars 21. Thus, cam 37 is mounted between bars 21. Pin 39 defines an axis of rotation forcam 37, which axis is fixed relative to the detent comprising roller 25, that is to say, is fixed relative to pin 23. The leading or effective portion of cam 37 comprises a pointed portion 41 having its leading edge at the intersection of converging'convex surface 43 and concave surface 45. Convex surface 43 is of generally greater radius of curvature than concave surface 45 adjacent the line of convergence of the two surfaces. Concave surface 45 adjacent the line of convergence is so Patented Dec. 30, 1958 spaced from pin 39 and of such curvature that in the position shown in Figure 2, roller 25 is received within concave surface 45. Convex surface 43 is so curved and spaced from pin .39 as to occupy a position relative to roller. 25 whichwas-formerly occupied bylower portion 35 of notch 31 and a portion of.lockbar.29 adjacent lower portion 35. i

As best seen in Figures. 3 and- 4, cam 37.;is provided with alaterally extending bar 47 fixed relative thereto. At its outer end, bar 47 carries a hand lever" 49 which 18 thus laterally spaced from cam 37 outwardly beyond both swing bars 21. .Lever 49 is generally parallel to the side faces of cam 37, and in its region adjacent bar 47 lS disposed generally parallel-to the greatest length. of cam 37. It will be seen by comparison of Figures 1 and 2 that cam 37, pin 39, bar 47 and lever 49 are so related to each other that earn 371W1ll ordinarilly hangdownward, as seen in Figure l,.,under-the influence of the weight of lever 49, and that lever: 49 must .deliberately be raised in order to position the partsas shown in FigureZ.

The operation of the novel safety device of the present invention is as follows:

Lock bar 29 leans by gravity on roller 25;-and when door 13 is raised, the inner side of bar 29 rolls'up on roller 15 until roller isdisposed in a-notch31 correspending .to the desired open height of the door. rThe parts then rest in this position; or if the counterweight does not balance the weight of the door, then the door may be returned slightly under the influence of gravity,

thus swinging lock bar 29 and swing bars 21 into a somewhat more closely aligned relationship than is shown in Figure 1, or until aportion of the assembly comprising lock bar 29 and swing bars 21 contacts the inner edge of thelower flange of channel member 7. In any event, upper portion 33 of notch31 is and remains in contact with roller 25 when the parts are positioned as shown in Figure l.

The parts remain in this position while the operator performs work in tire box 3 and if need be places his hands or arms belowdoor 13. If cable 11 should break at this time, the full weight of door 13 will be transferred to lock bar 29and door 13 will be held against falling. The sudden pull on lock bar 29thus exerted mightotherwisetend to bounce roller 25 and notch 31 out of contact with each other were not for the fact that swing bars 21 have pivoted downwardly, either during initial positioning of roller 25 in notch 31 or. in connection with the suddenpull exerted by the full weight of door 13, to the point that roller. 25 is effectively locked in notch 31 by virtue of the fact that substantial movement of lock bar 29 in a counterclockwise direction as seen in Figure 1 is prevented by the lower flange of channel member 7.

In the ordinary case, of course, cable 11 will not break; and hence, when the operator is ready to close door 13, he raises hand lever 49 to the position shown in Figure 2. Uponupward swinging movement of lever 49 from the position shown in Figure l to the position shown in Figure 2, cam 37 is rotated about pin '39 clockwise as seen in these two figures, with the result that pointed portion 41 is in effect forced between lock bar 29 and roller 25 to disengage these two parts from each other. The axes of cam 37 and roller 25 are fixed relative to each other; and hence, it is not necessary thatby the sliding contact of convex surface 43 with lower portion of notch 31, particularly at the intersection of lower portion 35 and the straight inner side of bar 29. During this disengaging movement, swing bars 21 are free to swing counterclockwise as seen in Figure 2, so as to displace roller 25 a distance from the lower flange of channel member 7 sufficient to permit free downward movement of lock bar 29. Thus, it will be seen that the purpose of concave surface 45 of cam 37 is primarily moved from beneath door 13 and moved in apositive and a deliberate upward movement so as to operate .lever 49. It should be further noted that this single; movement of lever 49 entirely deactivates the safety device of the present invention, and thatthat safety device is automatically engaged or rendered operative upon opening of the door.

From a consideration of the foregoing description, it will be evident that all of the initially-recited objects have been achieved by the present invention.

Although the present invention has been described in conjunction with a preferred embodiment, it is to be understood that modifications and variations may be made without departing from the spirit and scope of the invention, as those skilled in this art will readily understand. Such modifications and variations are to be considered within the purview and scope of the present invention as defined by the appended claims.

What is claimed is:

1. Apparatus for releasably retaining a vertically movable closure member in an upper position, comprising in combination a frame,.a detent mounted on said frame,

a lock bar pivotally mounted on and extending upwardly from said closure member, said lock bar having at least one notch adapted to engage over said detent to maintain said lock bar and closure member in anupper position, and a cam mounted on said frame for rotation about an axis fixed with respect to said detent, said cam having a portion so disposed that upon rotaton of said cam in one direction said portion moves between said detent and said lock bar to separate said detent and said notch to permit downward movement of said lock bar and clo sure member, and means for rotating said cam.

2. The invention of claim 1, said means for rotating said cam comprising a manually operable handle attached to said cam.

3. The invention of claim 2, said frame comprising a pair of spaced members, said cam and detent being mounted between said pair of spaced members, said lock bar being disposed between said pair of spaced members, and said handle being disposed laterally outwardly of said pair of spaced members.

References Cited in the file of this patent UNITED STATES PATENTS 2,029,818 Fleming Feb. 4, 1936 2,567,029 Sauter Sept. 4, 1951 2,660,765 Carlson Dec. 1, 1953 

